Doubt About Life On Europa

From: UFO UpDates - Toronto <ufoupdates@virtuallystrange.net>
Date: Wed, 28 Nov 2001 05:16:59 -0500
Fwd Date: Wed, 28 Nov 2001 05:16:59 -0500
Subject: Doubt About Life On Europa
http://www.tucsoncitizen.com/local/11_21_01europa.html
UA Study Casts Doubt About Life On Jupiter's Moon Europa
MARI N. JENSEN
Citizen Staff Writer
Nov. 21, 2001
A study by two University of Arizona planetary scientists shows
the icy crust covering Jupiter's moon Europa is thicker than
some scientists had hoped, making it less likely the moon
harbors life.
Europa is a target in the search for extraterrestrial life
because scientists think an ocean lies under its layer of frozen
water.
"Where there is liquid water, there is the possibility of life,"
said University of Arizona planetary scientist Elisabetta
Pierazzo.
The study by Pierazzo and co-author Elizabeth Turtle shows the
ice crust is at least 2 1/2 miles thick. Some scientists had
thought the crust might be less than a mile thick.
Because sunlight and organic material penetrate thin ice more
easily, scientists suggest the thinner the ice, the more likely
Europa's ocean harbors life. A thick ice layer also would make
it harder for a space probe to explore Europa's underwater
world.
Turtle said her team's finding is a good first step in resolving
the thickness controversy.
"We can't get maximum, but we can get a minimum," she said.
Jupiter, its great red spot and four moons are shown by Galileo.
Europa, whose icy crust is being studied by two University of
Arizona experts, is the moon second from the top.
Slightly smaller than our own moon, Europa is the fourth largest
of Jupiter's 16 known moons.
Images of Europa taken by the Galileo spacecraft show its
surface has large impact craters and at least six have small
peaks in the center. The peaks formed within minutes after a
comet smashed into the planet, much as slow-motion photographs
of a rock tossed into a pond show a central splash of water
upward in addition to the spreading circles of waves, Turtle and
Pierazzo said.
But in a watery surface, the central splash subsides. On a solid
surface, the material pushed up by such an explosive impact
remains. So Turtle and Pierazzo decided to calculate how deep
the ice had to be for central peak craters to form on Europa.
By running computer simulations of comet impacts, the team found
that the craters with central peaks had to be formed on ice at
least the 2 1/2 miles thick.
The team's report is in the Nov. 9 issue of the journal Science.
Turtle and Pierazzo's next step may settle the
thin-crust-vs.-thick-crust debate.
The two plan to study the rest of the crater creation process.
Turtle said preliminary results suggest that Europa's ice may be
about six miles thick.
UFO UpDates thanks:
The Anomalist - http://www.anomalist.com/
for the lead.....
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